How Many Gallons In a 500 lb Propane Tank? (Propane Tank Sizes)

How Many Gallons In a 500 lb Propane Tank

If you’re looking to fuel large appliances or heat significant areas with propane on a regular basis, then you’re going to need a pretty big tank.

Getting a size that is fit for purpose can be tricky so you might be wondering, how many gallons are there in a 500 lb propane tank?

A 500 lb propane tank can hold around 120 gallons of propane fuel, although the most common tank size that you will find is labelled as a 420 lb tank and holds about 85 gallons. In reality, a 500 lb propane tank is about 80% full, so the most you can put in is 100 gallons. Tanks at this size tend to be measured in terms of the number of gallons that they hold rather than their weight in pounds.

This article will give you all of the information that you need about propane tanks that carry around 500 lbs in weight, in particular the most common 420 lb size.

Read on to find out how much fuel they can hold, how long they are likely to last, how to move and store this size of tank, and how to get one topped up when it runs out.

How Much Fuel Do 500 lb Propane Tanks Hold?

Once you get into the range of propane tanks that are larger than around 100 lb in weight capacity, they are usually measured in the number of gallons that they can carry. A 500 lb propane tank would hold about 120 gallons of propane.

You will be more likely to find 420 lb tanks (120-gallon tanks) which can contain about 100 gallons when full.

You can definitely store a lot of fuel inside of a tank of this size. They are best suited for moderate heating purposes, hot water, fireplaces, industrial cooking equipment, or kitchen ranges, and they can last a long time before needing to be filled up.

Read also: Cheapest Propane Refill Near Me (Tanks Exchange Locations)

How Big is a 500 lb Propane Tank?

A tank of around this size will be quite large but the exact dimensions are different depending on the shape. Most of these tanks are vertical but some are horizontal, meaning they are longer than they are tall. The average measurements for a vertical 420 lb or 120-gallon propane tank are:

  • Width: Approximately 30 inches
  • Depth: Approximately 30 inches
  • Height: Approximately 55 inches.

A horizontal 120-gallon propane tank is likely to measure:

  • Width: Approximately 66 inches
  • Depth: Approximately 24 inches
  • Height: Approximately 24 inches

These tanks are certainly too large to be safely lifted by one person and will not fit comfortably into a standard family vehicle, even when empty.

How Heavy is a 500 lb Propane Tank?

Tanks of this size are obviously heavy when they are full but even an empty tank will have a considerable weight to it. The total weight of the tank will be a combination of the weight of the fuel and the weight of the tank itself.

Every propane tank will have a different empty weight, which is usually referred to as the “tare weight”, or TW. The TW of a vertical 120-gallon propane tank is usually around 175 pounds and, with a full 420 lbs of fuel, that makes the total weight of one of these tanks around 600 lbs when it is full.

A tank of this size is too heavy for a single person to safely manoeuvre and it contains too much propane to be inside of an enclosed vehicle when full. Transporting and storing propane tanks of this size needs to be done with care, taking into account proper safety precautions.

How Do You Transport a 500 lb Propane Tank?

You should not transport more than 90 lbs of total propane weight inside of an enclosed vehicle, so a propane tank of this size will need a different mode of transport. The back of a pickup truck or a flatbed is best for moving any tank that contains more than 90 lbs of propane.

You will likely need the assistance of a forklift to pick up any tank larger than 100 pounds and you need to be sure about the transportation laws in your area. Some states won’t allow large propane tanks to be transported if they are more than 10% full.

When you are transporting a propane tank you need to make sure that it remains upright and in the vertical position throughout the entirety of the journey. It should be tightly and reliably secured in place in a way that doesn’t allow it to move around, and it should not be left unattended.

Read also: How To Store Propane Tanks In Hot Weather: Storage Safety Tips

Where Should You Store a 500 lb Propane Tank?

You should not store large propane tanks inside of a home, shed, or garage as that would put them at greater risk of ignition in the case of a leak occurring. Instead, you should keep your propane tanks outside in a dry, well-ventilated area.

A propane tank should always be kept on a flat surface that is out of the elements as much as possible.

How Long Will a 500 lb Propane Tank Last?

If you are looking to get hold of a tank this size, you will want to know how long it is going to last. The amount of time that you will get out of your tank depends entirely on what it is being used for.

High energy usage appliances will burn through fuel more quickly than smaller, lower-energy appliances.

A large, professional grill might burn through around 4 pounds of propane every hour whereas the average propane water heater uses between 1 and 2 pounds to heat up a 50-gallon tank.

An industrial space heater might use 12 pounds an hour, but a home furnace usually burns just over 4 pounds hourly.

For these uses, a 500 lb propane tank is likely to last for approximately:

  • Propane Water Heater: 500 hours
  • Professional Grill: 200 hours
  • Home Heating: 120 hours
  • Industrial Space Heater: 35 hours

To heat an entire home, a 500 lb propane tank is probably going to need topping up multiple times a year, but they can last for a long time when used with professional grilling equipment or individual heating appliances.

You should refer to the BTUs of your appliances to find out exactly how long your tank will last.

What Do You Do When Your 500 lb Propane Tank Runs Low?

Unlike smaller tanks, it is quite challenging to transport an empty 500 lb propane tank to a refilling station, so it is generally easier to pay a company to come out and refill it for you.

Often, the company that sold you your tank in the first place will make it seem like they are the only ones who will be able to refill it as well, but there are a lot of companies that are happy to fill up any make or model of tank for you.

You will need to search for a company that offers large tank refills as there are laws and regulations about transporting certain quantities of propane. Bringing over 100 lbs of propane to you will often require a specialist.

Because of the need for transportation on top of the cost of the propane itself, prices can vary massively so you will need to get a quote from an individual company to find out how much you will need to pay.

Read also: How Much Does It Cost To Fill A Propane Tank For A House

How Do You Know How Much Propane Is Left in a 500 lb Tank?

You don’t really want to allow your tank to run completely dry and it can be difficult to schedule a top-up for exactly the right time, so you will need to know how to determine the amount of fuel that is left on your tank.

A 500 lb tank can be very difficult to weigh, so it is best to use a tank gauge instead. Most larger tanks come with a gauge on the top but you can purchase them separately as well.

A propane tank gauge essentially gives a percentage that tells you how full the tank is at that moment. Anything below 20% is usually the right time to start looking for a refill.

How Do You Calculate How Much Fuel a 500 lb Propane Tank Has Left?

To figure out the weight of fuel that you have left, you can simply multiply the total capacity of the tank by the percentage that is shown on the tank gauge. You can use a decimal to make this easier (10% is equal to 0.1, 20% is equal to 0.2, etc.).

For a 120 lb tank, 10% on the gauge means that you have 12 lbs of fuel left in the tank. 0.1 X 120 = 12. 20% means that you have 24 lbs left because 0.2 X 120 = 24.

Once you know how many pounds of fuel you have, you can also figure out how many BTUs that is, and therefore how long your tank is going to last with your appliances.

10% of a 120 lb tank is 12 lbs of fuel and one pound of propane contains 21,600 BTUs. Therefore 12 lbs of propane mean that you have 259200 BTUs remaining.

Read also: Blue Rhino Propane Refill Near Me (Cost, Exchange, Coupon, Walmart, Home Depot)


In a 500 lb propane tank you will be able to store around 120 gallons of propane. The most common tanks around this size are labelled as 420 lb tanks, or 120-gallon tanks, which actually carry about 100 gallons of fuel when they are full.

These tanks are pretty large and quite heavy, so they need to be handled and transported with care. It is important that you know and understands the legal limits for propane transportation in your area.

A tank this size can fuel large appliances for a long time, but it will likely need to be topped up pretty regularly if you are intending to heat your entire home with one.


Mike Gilmour

Hi, I'm Mike, co-founder, and editor of RV and Playa. My passion is traveling (with my RV) and enjoying the day at the beach (Playa)! Well, I originally created this blog as a way to share what I've learned by experimenting with the RV lifestyle, and I want to help others develop in life through new skills and opportunities.

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